segunda-feira, 17 de maio de 2010

7 incredible survival tactics of frogs

Feared by most women, the frogs are everywhere and have been able to fill most of the continents in the blink of an eye. Although they originate in the tropical regions of South America, the amphibian species of Bufonidae spread to all corners of the Earth in just 10 million years - a relatively short period of evolutionary point of view. With an eye on this expansiveness, the scientific site Live Science reported seven factors chosen by the scientists who made possible the success of the frogs.

The approximately 500 known species of frogs are extremely diverse, both in features, the type of habitat and range. "Some groups of amphibians are distributed worldwide, others do not," said evolutionary biologist Ines Van Bocxlaer, of Vrije University Brussel, Belgium.

"We want to find out why frogs have achieved a major expansion while other amphibians such as frogs of the Dendrobatidae family, were in just one area?" He asked.

From this, biologists reconstructed the evolutionary history of frogs and attempted to identify seven qualities that may have allowed the frogs colonize larger areas than other species. Know the reasons:

1 - Ability to live well on dry land
At first, the toads were confined to the tropics because of the constant need for water and moisture, but when some species have evolved the ability to live in drier, they expanded to other regions.

2 - Body size
Because of its size, the frog balloon can hold more water and lose relatively less water on the surface (frogs lose water through tiny pores in the skin). Therefore, this capability allows the species to live in a wide range of habitats including drier sites.

3 - Parotoid gland
These glands are the large blocks behind the bulbous eyes of frogs. Frogs found in sugarcane, the glands secrete toxicinas to defend the frog from predators and also works in the hydration of the animal. The evolution of this tissue increased the area of abundance of toads.

4 - Body Fat inguinal
This separate type of body fat allows frogs store more fat and save the extra energy reserves. "More power allows you to travel long distances," said Ines Van Bocxlaer.

5 - Ability to lay eggs
Originally, the toads had a very particular about where they would deposit their eggs. But while some species have evolved the ability to lay eggs in any puddle or something, this factor has facilitated its spread to all continents.

6 - Egg production on a larger scale
When the frogs began to produce large litters with thousands of eggs, instead of the mother only to worry about giving care to a small number of offspring, the species were able to travel with greater ease and greater distances.

7 - Tadpoles
Some tadpoles, called endotophous, feed on the nutrients from the mother, but Exotrophous tadpoles feed on nutrients out of the nest. Frogs feature Exotrophous may have more cubs in dry or wet, facilitating the breeding sites.

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